Thermal Distribution Simulation

[tonyj.moore]

Hello all, I am attempting to do a thermal simulation on a wax melting hopper that I am making and was wondering if I could get some help.

So we are heating water up to at least 180 degrees on the inside of the body to melt the wax on the outside. We are using a 1500 Watt 120 volt heating element. I applied a heat source load of 1500W to the element and applied multiple types of loads to the inside faces of the  hopper.

The problem I am having is that the model is mainly one temperature and I know for a fact that the valves and pipes below the hopper would not be 180 degrees. I can email the file or share it on here if someone could help but I attached a couple screen shots of one of the many simulations I have so far.

Lastly, can you set the amount of time that a certain heat is applied to a surface or component?

Thanks!

  Tony

[Anonymous · Accepted solution]

I see you have 1 convection load in your model. I'm guessing that's for the water in the hopper. To get an accurate idea of the valve (and hopper) temperature, you will also need a convection load for dissipating heat from the valve (and hopper) into the surrounding air.

As far as I know, Fusion's thermal simulation will only handle steady state conditions.

What are you trying to learn from the simulation? Melt time? Temp distribution throughout the hopper?

[tonyj.moore]

Thanks for the reply,

Yes, I am looking for the time it takes the inside of the hopper to reach 180 degrees F and the thermal distribution. The thermal distribution is the most important to me. I will apply convective loads to the outside and see how that works.

[tonyj.moore]

Also, can you set a duration on how long the heating element is on for? For example, it takes the 2.5 gallons of water in the hopper 39 minutes to heat up to 180. Can I simulate a time frame for the analysis?

[Anonymous]

I'm by no means an expert on what Fusion simulation can and can't do, but I don't think it will be able to tell you how long it will take to heat the water to 180. I think it will only be able to give you the steady state temperature distribution.

I think your best bet on figuring out the time to 180F is a hand calculation of how much energy (watt*hour) it takes to heat however many pounds of water you have from ambient temp to 180F, then dividing by your heater power (1500W). This will of course be a low estimate, since some of the energy will be dissipated into the hopper and surrounding air while it's heating. But, it will at least tell you if it's going to take minutes or hours.

[John_Holtz]

Hi Tony,

As Jason pointed out, the thermal analysis in Fusion will only calculate the steady state results - what happens after the loads have been applied for an infinite length of time. So if the heater cycles off and on, you might be able to get an "average steady state temperature result" by entering the average wattage over the entire cycle. (If the heater is on for 75% of the time, try entering a heat source of 0.75*1500 W.)

More importantly, how is the heat transmitting from the heating element to the tank? In the images you provided, the heating element is 341,000 F (significantly hotter than the surface of the Sun ). In reality, the heat is transmitted through the water to the tank, so the element does not get as hot. Do you have the water in the simulation? Or you could apply the heat source to the wetter surface of the tank instead of applying it to the heater and including the water volume. That would be the same as saying "the 1500 W from the heater travels through the water and appears on the wall".

Another aspect that you may not be able to model is this. The water will move around due to buoyancy, so it carries heat differently than a "solid" mass of water in the simulation would predict. You will not be able to include those effects accurately in Fusion. (Autodesk CFD is the right software to handle that computation.) You may be able to "fudge" it my increasing the thermal conductivity of the water. This will increase the rate that heat conducts through the water, sort of like the increase rate of heat transfer through the water due to the motion of the water.